CA1255071A - Process for the preparation of titanium dioxide - Google Patents
Process for the preparation of titanium dioxideInfo
- Publication number
- CA1255071A CA1255071A CA000468773A CA468773A CA1255071A CA 1255071 A CA1255071 A CA 1255071A CA 000468773 A CA000468773 A CA 000468773A CA 468773 A CA468773 A CA 468773A CA 1255071 A CA1255071 A CA 1255071A
- Authority
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- Prior art keywords
- sulphuric acid
- sulphate
- acid
- process according
- metal
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G23/00—Compounds of titanium
- C01G23/04—Oxides; Hydroxides
- C01G23/047—Titanium dioxide
- C01G23/053—Producing by wet processes, e.g. hydrolysing titanium salts
- C01G23/0532—Producing by wet processes, e.g. hydrolysing titanium salts by hydrolysing sulfate-containing salts
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1236—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching
- C22B34/124—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching using acidic solutions or liquors
- C22B34/125—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching using acidic solutions or liquors containing a sulfur ion as active agent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/129—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining metallic titanium from titanium compounds by dissociation, e.g. thermic dissociation of titanium tetraiodide, or by electrolysis or with the use of an electric arc
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Inorganic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
- Catalysts (AREA)
Abstract
ABSTRACT
In the preparation of titanium dioxide comprising autothermically digestion a titanium-containing raw material with sulphuric acid to form a solid relatively easily soluble digestion cake containing titanyl sulphate, extracting metal sulphates from this cake by water or dilute sulphuric acid, separating the undissolved residues and, optionally after crystallization of iron sulphate heptahydrate, hydrolyzing the titanyl sulphate to produce titanium oxide hydrate, and calcining the titanium oxide hydrate to titanium dioxide, the improvement which comprises adding to the raw material a metal sulphate and effecting the autothermic decomposition with sulphuric acid of about 80 to 88% concentration. Advantageously the acid is obtained by mixing dilute acid with concentrated sulphuric acid or oleum, some of the dilute acid and metal sulphate coming from a by-product filter cake produced in the course of the process.
In the preparation of titanium dioxide comprising autothermically digestion a titanium-containing raw material with sulphuric acid to form a solid relatively easily soluble digestion cake containing titanyl sulphate, extracting metal sulphates from this cake by water or dilute sulphuric acid, separating the undissolved residues and, optionally after crystallization of iron sulphate heptahydrate, hydrolyzing the titanyl sulphate to produce titanium oxide hydrate, and calcining the titanium oxide hydrate to titanium dioxide, the improvement which comprises adding to the raw material a metal sulphate and effecting the autothermic decomposition with sulphuric acid of about 80 to 88% concentration. Advantageously the acid is obtained by mixing dilute acid with concentrated sulphuric acid or oleum, some of the dilute acid and metal sulphate coming from a by-product filter cake produced in the course of the process.
Description
lI.r~ 7 ~1 Process for the preparation of titanium ioxide -The present invention relates to a process for the preparation of titanium dioxide by autothermic dig~s-tion of raw materials containing titanium by means ofsulphuric acid to form a solid, relatively easily soluble digestion cake, extraction of the metal sulphates from this cake with water or dilute sulphuric acid, removal of the undissolved residues and, optionally after crystal-lization f iron sulphate heptahydrate, hydrolysis of the titanyl sulphate and calcining of the hydrated titanium oxide to titanium dioxide.
According to the present state of the art (Ullmanns Enzyklopadie 4, Edition 1979, Volume 18, pages 574 - 576), autothermic digestion of titanium raw materials to produce a solid, relatively easily soluble digestion cake requires the use of sulphuric acid at a concentration of at least 88 to 92~ at the beginning of the reaction.
This sulphuric acid is normally produced by the addition of water or steam to a mixture of a 90 to 98% sulphuric acid and the ground up TiO2 raw material. The heat produced from mixing water and sulphuric acid is responsible for a sufficiently sharp rise in temperature to start the exo-thermic reaction of TiO2 raw material with sulphuric acid to form metal sulphates and water. The heat of reaction released raises the temperature of the mixture to 170 -220C and causes extensi~e evaporation of the wateroriginally present and the water formed during the reaction. In order to obtain the digestion cake in a relatively easily soluble, porous state, air is continuously blown through the mass during the reaction if the process of digestion is carried out discontin-uously.
In a process of discontinuous di~estion, the formation of a solid, gas permeable cake is extremely desirable. If the reaction mass is still in the form of a viscous liquid at a relatively high temperature, bubbles of steam are liable to form in the mass and the sudden release of pressure in these bubbles is liable to take place Le A 22 712 _ ~¦"--d~$~[)7 ~L
According to the present state of the art (Ullmanns Enzyklopadie 4, Edition 1979, Volume 18, pages 574 - 576), autothermic digestion of titanium raw materials to produce a solid, relatively easily soluble digestion cake requires the use of sulphuric acid at a concentration of at least 88 to 92~ at the beginning of the reaction.
This sulphuric acid is normally produced by the addition of water or steam to a mixture of a 90 to 98% sulphuric acid and the ground up TiO2 raw material. The heat produced from mixing water and sulphuric acid is responsible for a sufficiently sharp rise in temperature to start the exo-thermic reaction of TiO2 raw material with sulphuric acid to form metal sulphates and water. The heat of reaction released raises the temperature of the mixture to 170 -220C and causes extensi~e evaporation of the wateroriginally present and the water formed during the reaction. In order to obtain the digestion cake in a relatively easily soluble, porous state, air is continuously blown through the mass during the reaction if the process of digestion is carried out discontin-uously.
In a process of discontinuous di~estion, the formation of a solid, gas permeable cake is extremely desirable. If the reaction mass is still in the form of a viscous liquid at a relatively high temperature, bubbles of steam are liable to form in the mass and the sudden release of pressure in these bubbles is liable to take place Le A 22 712 _ ~¦"--d~$~[)7 ~L
-2-explosively, with undesirable consequences.
When digestion is carried out as a continuous process in paddle screws or similar apparatus, it is desirable to obtain a friable reaction product which can easily be suspended in the ~essel in which the product is dissolved.
If TiO2 production is to be carried out with an aware-ness of environmental considerations, waste acid, sulph-uric acid recovered from the evaporation of waste acid, 1~ or relatively dilute sulphuric acid obtained from other sources such as installations for the purification of exhaust gases may usefully be employed for the diges-tion of the raw material containing TiO2. If 96 to 99~sulphuric acid is mixed with these acids instead of with water, they may only be used in very small quantities,but if oleum is mixed with acids containing less than 75%
H2SO4, considerably larger quantities of dilute acids or acids of medium concentration may be used. It may easily be calculated, however, that one important ecological aim, namely recovery of all the sulphuric acid from the Tio2 ~aste acid, cannot be achieved by this procedure since it is not practicable to evaporate waste acids to concentrations higher than 65~ H2SO4 (salt free) for reasons of the solubility of iron sulphate. Further evaporation to increase the concentration of the acid to above 65% after separation of the metal sulphate would require considera~ly greater ef~ort and cost.
It is an object of the present invention to provide a process enabling the decomposition of TiO2 raw materials to be carried out with lower sulphuric acid concentrations at the beginning of the reac~ion and yet resulting in a solid, gas permeable, readily soluble decomposition cake if the process is carried out batchwi5e or a solid, friable cake if it is carried out continuously~
It has now surprisingly been found that this object may be achieved if the digestion reaction is carried out in the presence of metal sulphates.
Le A 22 712 The present invention therefore relates to a process for the preparation of titanium dioxide by autothermic digestion of raw materials containing titanium by means of sulphuric acid to Eorm a solid, relatively easily soluble di~estion cake, extraction of the metal sulphates from this cake by solution with water or dilute sulphuric acid, removal of the undissolved residues and possibly of iron sulphate heptahydrate after the latter has been cx~stallized, hydrolysis of the titanyl sulphate and calcining of the hydrated oxide of titanium to titanium dioxide, characterized in that the reaction mixture contains sulphuric acid at a concentration of 80 to 88~ and metal sulphates at the beginning of the digestion reaction. ~y adjustin~ the sulphuric acid concentration to only 80 to 88~ instead of 88 to 92% at the beginning of the reaction, it is possible to use substantially larger quantities of 20 to 75~ sulphuric acid for the diges-tion of TiO2 raw materials than has hitherto been possible.Moreover, the presence of metal sulphates slows down the reaction at the beginning in the case of batchwise digestion and improves the consistency and solubility in water of the ripened cake.
The quantity of metal suIphates to be introduced is to be determined by preliminary tests for the particular TiO2 raw materials used. Over a wide range, the only factor influenced is the consistency o~ the digestion cake.
The quantity of metal sulphates added is advantageously adjusted to the required sulphuric acid concentration and the particular TiO2 raw materials used. It is only when relatively large quantities of sulphate are used that a substantial reduction in Tio2 yield is observed, probably due to insuf f icient contact between acid and TiO2 ra~
material as a result of the dilution effect of the metal sulphates or due to a reduction in the maximum temperature during digestion. The metal sulphate cGntent of the digestion mixture at the beginning of the reaction is generally from 0.5 to 25~, preferably from 2 to 15%.
Le ~ 22 712 The 80 to 88% sulphuric acid put into the process may be obtained by mixing 95 to 99% sulphuric acid with 20 to 75~ sulphuric acid or, if available, by mixin~ oleum with 20 to 75% sulphuric acid. This means that the process according to the invention may obviate the use of an oleum plant.
The metal sulphates, in particular iron sulphate, aluminum sulphate and magnesium sulphate, may be dissolved in the 20 to 75% sulphuric acid or suspended in solid form.
They may also be introduced into the digestion mixture in the form of solids together with the Tio2 raw material, in which case they may be used either as filter cake obtained Erom concentration of the waste acid by evaporation or as iron sulphate monohydrate obtained from the dehydration of iron sulphate heptahydrate. Other metal sulphates low in or free from water of hydration may also be used for the purpose of this invention.
The 20 to 75~ sulphuric acid used for the purpose of this invention may suitably be so-called TiO2 waste acid or waste acid concentrated by evaporation, containing dissolved metal sulphates. Other 20 to 75% spent aeids of inferior quality may also be used.
According to one partieularly preferred embodiment of the proeess of this invention, at least a proportion of the 20 to 75% sulphurie aeid and of the metal sulphates is used in the ~orm of the metal sulphate/sulphuric acid suspension obtained from the concentration of TiO2 waste aeid by evaporation.
For eeonomieal reasons, it is particularly suitable to use metal sulphates obtained as filter eakes from the filtration o~ the evaporation-eoncentrated Ti~2 waste acid. Iron sulphate monohydrate as obtained from the dehydration of iron sulphate heptahydrate is also advantage-ous on account of its low water content.
3s If the reaction mixture contains salt, the diges-tion reaction may still be started in the usual manner by ~he injection of steam, the addition of water or the evolution of mixing heat from the acid.
Le A 22 712 ~P~$~ 037~
The advantages of the process accordin~ to the invention will be demonstrated in the following e~a~lples without restricting the scope of the invention as regards the metal sulphates put into the process, the acid concentration or the Tio~ raw materials.
Le A 22 712 iS637ilL
Example 1 (ComParison Example) 400 g of ground ilmenite (60.0~ Tio2, 9.3% FeO, 25.7 Fe2O3, 1.2S~ A12O3, 0.5% MgO) were mixed with 754 g of 96~
sulphuric acid in a Dewar vessel. The reaction was started by the addition oE 68 g of H2O. The calculated sulphuric acid concentration was at this stage 88% H2SO4.
Air was blown through the mixture during the reaction at the rate of 500 l/h. After 12 minutes, the mixture solidified at a temperature of 180C. The maximum 10temperature of 202C was reached after 13 minutes. After a ripening time of 3 hours, the cake was broken down and dissolved in water. Complete solution of the sulphate took 4 hours. The TiO2 yield was 93.6%.
Example 2 (ComParison Example) 15400 9 of ilmenite were mixed with 754 g of 96% H2SO4 by a procedure analogous to that of Example 1 but 129 g of H2O were added so that the starting concentration of H2SO4 was 82%. The mixture solidified at 173C but only after 25 minutes and after it had reached its temperature maximum at 176C at the end of a reaction time of 13 minutes. The cake took 5 hours to dissolve, The TiO2 yield was only 93.0%. The late onset of the solidification of the decomposition mass indicates the risk of explosive release of tension in the steam bubbles under industrial conditions of digestion.
Examele 3 400 g of ilmenite similar to that of Example 1 were mixed with 719.7 g of 96% H2SO4 and 117.6 g of filter cake obtained from the evaporation of waste acid (27.9~ H2SO4, 4 A12(SO4)3~ 9-4% MgS04 ~ 5.1% Tioso4 ) and 91.3 g of H2O were added. The sulphuric acid concentration was e4 . o~ H2SO4 at the onset of the reaction.
The reaction mixture solidified at 168C after 9 minutes.
The mixture reached its temperature maximum at 196C after 11 minutes. After a ripening time of 3 hours, the cake was dissolved in water over a period of 5 hours. The TiO2 yield ~based on the quantity o ilmenite put into the ~e ~ 22 712 7~ ~ SC~7~l process) was 95.4~.
Example 4 400 g oE the ilmenite were mixed with 467.6 g of sulphuric acid recovered from waste acid evaporation (65~
2 4 g 4 A12(SO4)3)) and 117.6 g of the filter cake described in Example 3. The reaction was started by the addition of 369.2 g of 27% oleum. ~he H2SO4 concentration was 82.0~. The reaction mixture solidified at 180C after 13 minutes. The temperature maximum was reached at the same time.
After a ripening time of 3 hours, the digestion cake was dissolved in water over a period of 3.5 hours. The TiO2 yield (based on ilmenite) was 94.5%.
It will be understood that the specification and ~5 e~amp~es are i~us~ati~e b~t no~ ~im ~a~i~e o~ t~
present invention and that other em~odiments within the spirit and scope o~ the in~entiGn will suggest them selves to those skilled in the art.
Le A 22 712 _
When digestion is carried out as a continuous process in paddle screws or similar apparatus, it is desirable to obtain a friable reaction product which can easily be suspended in the ~essel in which the product is dissolved.
If TiO2 production is to be carried out with an aware-ness of environmental considerations, waste acid, sulph-uric acid recovered from the evaporation of waste acid, 1~ or relatively dilute sulphuric acid obtained from other sources such as installations for the purification of exhaust gases may usefully be employed for the diges-tion of the raw material containing TiO2. If 96 to 99~sulphuric acid is mixed with these acids instead of with water, they may only be used in very small quantities,but if oleum is mixed with acids containing less than 75%
H2SO4, considerably larger quantities of dilute acids or acids of medium concentration may be used. It may easily be calculated, however, that one important ecological aim, namely recovery of all the sulphuric acid from the Tio2 ~aste acid, cannot be achieved by this procedure since it is not practicable to evaporate waste acids to concentrations higher than 65~ H2SO4 (salt free) for reasons of the solubility of iron sulphate. Further evaporation to increase the concentration of the acid to above 65% after separation of the metal sulphate would require considera~ly greater ef~ort and cost.
It is an object of the present invention to provide a process enabling the decomposition of TiO2 raw materials to be carried out with lower sulphuric acid concentrations at the beginning of the reac~ion and yet resulting in a solid, gas permeable, readily soluble decomposition cake if the process is carried out batchwi5e or a solid, friable cake if it is carried out continuously~
It has now surprisingly been found that this object may be achieved if the digestion reaction is carried out in the presence of metal sulphates.
Le A 22 712 The present invention therefore relates to a process for the preparation of titanium dioxide by autothermic digestion of raw materials containing titanium by means of sulphuric acid to Eorm a solid, relatively easily soluble di~estion cake, extraction of the metal sulphates from this cake by solution with water or dilute sulphuric acid, removal of the undissolved residues and possibly of iron sulphate heptahydrate after the latter has been cx~stallized, hydrolysis of the titanyl sulphate and calcining of the hydrated oxide of titanium to titanium dioxide, characterized in that the reaction mixture contains sulphuric acid at a concentration of 80 to 88~ and metal sulphates at the beginning of the digestion reaction. ~y adjustin~ the sulphuric acid concentration to only 80 to 88~ instead of 88 to 92% at the beginning of the reaction, it is possible to use substantially larger quantities of 20 to 75~ sulphuric acid for the diges-tion of TiO2 raw materials than has hitherto been possible.Moreover, the presence of metal sulphates slows down the reaction at the beginning in the case of batchwise digestion and improves the consistency and solubility in water of the ripened cake.
The quantity of metal suIphates to be introduced is to be determined by preliminary tests for the particular TiO2 raw materials used. Over a wide range, the only factor influenced is the consistency o~ the digestion cake.
The quantity of metal sulphates added is advantageously adjusted to the required sulphuric acid concentration and the particular TiO2 raw materials used. It is only when relatively large quantities of sulphate are used that a substantial reduction in Tio2 yield is observed, probably due to insuf f icient contact between acid and TiO2 ra~
material as a result of the dilution effect of the metal sulphates or due to a reduction in the maximum temperature during digestion. The metal sulphate cGntent of the digestion mixture at the beginning of the reaction is generally from 0.5 to 25~, preferably from 2 to 15%.
Le ~ 22 712 The 80 to 88% sulphuric acid put into the process may be obtained by mixing 95 to 99% sulphuric acid with 20 to 75~ sulphuric acid or, if available, by mixin~ oleum with 20 to 75% sulphuric acid. This means that the process according to the invention may obviate the use of an oleum plant.
The metal sulphates, in particular iron sulphate, aluminum sulphate and magnesium sulphate, may be dissolved in the 20 to 75% sulphuric acid or suspended in solid form.
They may also be introduced into the digestion mixture in the form of solids together with the Tio2 raw material, in which case they may be used either as filter cake obtained Erom concentration of the waste acid by evaporation or as iron sulphate monohydrate obtained from the dehydration of iron sulphate heptahydrate. Other metal sulphates low in or free from water of hydration may also be used for the purpose of this invention.
The 20 to 75~ sulphuric acid used for the purpose of this invention may suitably be so-called TiO2 waste acid or waste acid concentrated by evaporation, containing dissolved metal sulphates. Other 20 to 75% spent aeids of inferior quality may also be used.
According to one partieularly preferred embodiment of the proeess of this invention, at least a proportion of the 20 to 75% sulphurie aeid and of the metal sulphates is used in the ~orm of the metal sulphate/sulphuric acid suspension obtained from the concentration of TiO2 waste aeid by evaporation.
For eeonomieal reasons, it is particularly suitable to use metal sulphates obtained as filter eakes from the filtration o~ the evaporation-eoncentrated Ti~2 waste acid. Iron sulphate monohydrate as obtained from the dehydration of iron sulphate heptahydrate is also advantage-ous on account of its low water content.
3s If the reaction mixture contains salt, the diges-tion reaction may still be started in the usual manner by ~he injection of steam, the addition of water or the evolution of mixing heat from the acid.
Le A 22 712 ~P~$~ 037~
The advantages of the process accordin~ to the invention will be demonstrated in the following e~a~lples without restricting the scope of the invention as regards the metal sulphates put into the process, the acid concentration or the Tio~ raw materials.
Le A 22 712 iS637ilL
Example 1 (ComParison Example) 400 g of ground ilmenite (60.0~ Tio2, 9.3% FeO, 25.7 Fe2O3, 1.2S~ A12O3, 0.5% MgO) were mixed with 754 g of 96~
sulphuric acid in a Dewar vessel. The reaction was started by the addition oE 68 g of H2O. The calculated sulphuric acid concentration was at this stage 88% H2SO4.
Air was blown through the mixture during the reaction at the rate of 500 l/h. After 12 minutes, the mixture solidified at a temperature of 180C. The maximum 10temperature of 202C was reached after 13 minutes. After a ripening time of 3 hours, the cake was broken down and dissolved in water. Complete solution of the sulphate took 4 hours. The TiO2 yield was 93.6%.
Example 2 (ComParison Example) 15400 9 of ilmenite were mixed with 754 g of 96% H2SO4 by a procedure analogous to that of Example 1 but 129 g of H2O were added so that the starting concentration of H2SO4 was 82%. The mixture solidified at 173C but only after 25 minutes and after it had reached its temperature maximum at 176C at the end of a reaction time of 13 minutes. The cake took 5 hours to dissolve, The TiO2 yield was only 93.0%. The late onset of the solidification of the decomposition mass indicates the risk of explosive release of tension in the steam bubbles under industrial conditions of digestion.
Examele 3 400 g of ilmenite similar to that of Example 1 were mixed with 719.7 g of 96% H2SO4 and 117.6 g of filter cake obtained from the evaporation of waste acid (27.9~ H2SO4, 4 A12(SO4)3~ 9-4% MgS04 ~ 5.1% Tioso4 ) and 91.3 g of H2O were added. The sulphuric acid concentration was e4 . o~ H2SO4 at the onset of the reaction.
The reaction mixture solidified at 168C after 9 minutes.
The mixture reached its temperature maximum at 196C after 11 minutes. After a ripening time of 3 hours, the cake was dissolved in water over a period of 5 hours. The TiO2 yield ~based on the quantity o ilmenite put into the ~e ~ 22 712 7~ ~ SC~7~l process) was 95.4~.
Example 4 400 g oE the ilmenite were mixed with 467.6 g of sulphuric acid recovered from waste acid evaporation (65~
2 4 g 4 A12(SO4)3)) and 117.6 g of the filter cake described in Example 3. The reaction was started by the addition of 369.2 g of 27% oleum. ~he H2SO4 concentration was 82.0~. The reaction mixture solidified at 180C after 13 minutes. The temperature maximum was reached at the same time.
After a ripening time of 3 hours, the digestion cake was dissolved in water over a period of 3.5 hours. The TiO2 yield (based on ilmenite) was 94.5%.
It will be understood that the specification and ~5 e~amp~es are i~us~ati~e b~t no~ ~im ~a~i~e o~ t~
present invention and that other em~odiments within the spirit and scope o~ the in~entiGn will suggest them selves to those skilled in the art.
Le A 22 712 _
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In the preparation of titanium dioxide comprising autothermically digestion a titanium-containing raw material with sulphuric acid to form a solid relatively easily soluble digestion cake containing titanyl sulphate, extracting metal sulphates from this cake by water or dilute sulphuric acid, separating the undissolved residues and, hydrolizing the titanyl sulphate to produce titanium oxide hydrate, and calcining the titanium oxide hydrate to titanium dioxide, the improvement which comprises adding to the raw material a metal sulphate and effecting the autothermic decomposition with sulphuric acid of about 80 to 88%
concentration.
concentration.
2. The process according to claim 1, wherein before hydrolyzing the titanyl sulphate to produce titanium oxide hydrate, iron sulphate heptahydrate is crystallized.
3. The process according to claim 1, wherein the metal sulphate is present in about 0.5 to 25% by weight of the raw material.
4. The process according to claim 1, wherein the metal sulphate is present in about 2 to 15% by weight of the raw material.
5. The process according to claim 1, wherein the 80 to 88%
sulphuric acid is prepared by mixing oleum with 20 to 75%
sulphuric acid.
sulphuric acid is prepared by mixing oleum with 20 to 75%
sulphuric acid.
6. The process according to claim 5, wherein the 20 to 75%
sulphuric acid is TiO2 waste acid or TiO2 waste acid concentrated by evaporation, and contains metal sulphates in solution.
sulphuric acid is TiO2 waste acid or TiO2 waste acid concentrated by evaporation, and contains metal sulphates in solution.
7. The process according to claim 5, wherein the 20 to 75%
sulphuric acid is low grade spent acid.
sulphuric acid is low grade spent acid.
8. The process according to claim 5, wherein at least a portion of the 20 to 75% sulphuric acid and of the metal sulphates is in the form of a metal sulphate/sulphuric acid suspension obtained from concentration of TiO2 waste acid by evaporation.
9. The process according to claim 5, wherein the 20 to 75%
sulphuric acid contains metal sulphates in solution and in solid form.
sulphuric acid contains metal sulphates in solution and in solid form.
10. The process according to claim 1, wherein the metal sulphate is used in the form of a filter cake obtained from filtration of evaporation-concentrated TiO2 waste acid.
11. The process according to claim 1, wherein the metal sulphate used is iron sulphate monohydrate obtained by the dehydration of iron sulphate heptahydrate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19833343256 DE3343256A1 (en) | 1983-11-30 | 1983-11-30 | METHOD FOR PRODUCING TITANIUM DIOXIDE |
| DEP3343256.2 | 1983-11-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1255071A true CA1255071A (en) | 1989-06-06 |
Family
ID=6215622
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000468773A Expired CA1255071A (en) | 1983-11-30 | 1984-11-28 | Process for the preparation of titanium dioxide |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4663131A (en) |
| EP (1) | EP0147608B2 (en) |
| CA (1) | CA1255071A (en) |
| DE (2) | DE3343256A1 (en) |
| FI (1) | FI77831C (en) |
| NO (1) | NO164529B (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3627655A1 (en) * | 1986-08-14 | 1988-03-24 | Bayer Ag | METHOD FOR PRODUCING TITANIUM DIOXIDE PIGMENTS |
| CH672633A5 (en) * | 1987-11-23 | 1989-12-15 | Escher Wyss Ag | |
| DE3843846C1 (en) * | 1988-12-24 | 1990-04-12 | Bayer Ag, 5090 Leverkusen, De | |
| GB9119205D0 (en) * | 1991-09-09 | 1991-10-23 | Tioxide Group Services Ltd | Quench system |
| US5227032A (en) * | 1991-09-24 | 1993-07-13 | The United State Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Method for producing oxygen from lunar materials |
| WO1993018193A1 (en) * | 1992-03-09 | 1993-09-16 | Pivot Mining Nl | Acid washing of leached solids from the beneficiation of titaniferous ores |
| AU744330B2 (en) * | 1997-05-30 | 2002-02-21 | Kemicraft Overseas Limited | Continuous non-polluting liquid phase titanium dioxide process |
| US6048505A (en) * | 1997-06-16 | 2000-04-11 | Kemicraft Overseas Limited | Continuous non-polluting liquid phase titanium dioxide process and apparatus |
| DE10106539A1 (en) * | 2001-02-13 | 2002-08-22 | Kerr Mcgee Pigments Gmbh & Co | Process for the extraction of titanium dioxide from digestion residues of a sulphate process |
| AU2002952158A0 (en) * | 2002-10-18 | 2002-10-31 | Bhp Billiton Innovation Pty Ltd | Production of titania |
| DE10303287A1 (en) * | 2003-01-28 | 2004-07-29 | Sachtleben Chemie Gmbh | Improving filter cake neutralization in titanium dioxide production by sulfate process, involves using a basic-reacting solution or suspension in the membrane chamber filter press |
| DE102004019191B3 (en) * | 2004-01-27 | 2005-06-02 | Kronos International, Inc. | Powdered mixture for reducing the chromate content in cement contains a filter salt produced by concentrating diluted sulfuric acid, and a carrier material selected from hydrated lime, ground limestone and precipitated silicic acid |
| EA035074B9 (en) * | 2014-07-08 | 2020-05-15 | Авертана Лимитед | Extraction of products from titanium-bearing minerals |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR655905A (en) * | 1927-10-28 | 1929-04-25 | Roches Et Minerais Soc | Process for obtaining white pigment based on pure titanium oxide |
| US2112966A (en) † | 1937-04-02 | 1938-04-05 | Du Pont | Decomposition of titanium ores |
| US2180961A (en) * | 1938-10-07 | 1939-11-21 | Du Pont | Production of water-soluble titanium compounds |
| US2774650A (en) * | 1953-05-01 | 1956-12-18 | Nat Lead Co | Method for decomposition of titaniferous ores |
| FR1548343A (en) * | 1967-07-07 | 1968-12-06 | ||
| US4038363A (en) * | 1975-10-21 | 1977-07-26 | Quebec Iron & Titanium Corporation-Fer Et Titane Due Quebec, Inc. | Upgrading sorelslag for production of synthetic rutile |
| US4288415A (en) * | 1979-08-10 | 1981-09-08 | Nl Industries, Inc. | Process for manufacturing titanium compounds using a reducing agent |
| DE2951799A1 (en) * | 1979-12-21 | 1981-07-02 | Bayer Ag, 5090 Leverkusen | METHOD FOR PRODUCING A HYDROLYZABLE TITANYL SULFATE SOLUTION |
-
1983
- 1983-11-30 DE DE19833343256 patent/DE3343256A1/en not_active Withdrawn
-
1984
- 1984-11-15 NO NO844563A patent/NO164529B/en unknown
- 1984-11-17 EP EP19840113925 patent/EP0147608B2/en not_active Expired - Lifetime
- 1984-11-17 DE DE8484113925T patent/DE3465342D1/en not_active Expired
- 1984-11-20 US US06/673,244 patent/US4663131A/en not_active Expired - Fee Related
- 1984-11-28 FI FI844672A patent/FI77831C/en not_active IP Right Cessation
- 1984-11-28 CA CA000468773A patent/CA1255071A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4663131A (en) | 1987-05-05 |
| FI844672L (en) | 1985-05-31 |
| EP0147608B1 (en) | 1987-08-12 |
| EP0147608B2 (en) | 1991-04-17 |
| FI77831B (en) | 1989-01-31 |
| FI77831C (en) | 1989-05-10 |
| FI844672A0 (en) | 1984-11-28 |
| NO164529B (en) | 1990-07-09 |
| NO844563L (en) | 1985-05-31 |
| DE3465342D1 (en) | 1987-09-17 |
| DE3343256A1 (en) | 1985-06-05 |
| EP0147608A1 (en) | 1985-07-10 |
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